1985-1986 Honda Fourtrax 125 TRX125 Shop Manual, Page 189Get this manual
REAR WHEEL BRAKEDRIVE MECHANISM
loosen the rear brake adjusting nu tLoosen the drive chain adjusting nut and bearing holder mounting bolts
DRIVE CHAIN ADJUST ING NUT BEARING HOLDER BOLTS
CHAIN CLI P
Remove the chain clip, master link and drive chain
MASTER LINK
LOCK NUT SPANNER, 41 mm 079169580200 or AXLE HOLDER NUT WRENCH O.79 16958010A (U.S .Aonlyl